Wave propagation refers to any of the ways in which waves travel.
- Electromagnetic radiation propagates through space, carrying electromagnetic energy in the form of electromagnetic waves.
- The propagation of electromagnetic radiation through space is sometimes described in terms of photons rather than waves.
- Propagation of electromagnetic waves may occur in a vacuum as well as through different materials. Other wave types such as sound waves cannot propagate through a vacuum and need a transmission medium.
- All forms of electromagnetic radiation propagate in similar ways whether they are radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.
- Oscillation relative to the direction of propagation can be in the form of longitudinal or transverse waves.
- Light waves across the electromagnetic spectrum behave in similar ways. When a light wave encounters an object, it may be transmitted, reflected, absorbed, refracted, polarized, diffracted, or scattered depending on the composition of the object and the wavelength of the light.